Congener-specific numbering systems for the environmentally relevant C₄ through C₈ perfluorinated homologue groups of alkyl sulfonates, carboxylates, telomer alcohols, olefins, and acids, and their derivatives

Abstract

We introduce a congener-specific numbering system for the C₄ through C₈ perfluorinated homologue groups of alkyl sulfonates, carboxylates, telomer alcohols, olefins, and acids, and their derivatives. Increasing length of the carbon chain beyond C₃ leads to a corresponding rapid increase in the number of potential isomers (C₄ = 4, C₅ = 8, C₆ = 17, C₇ = 39, and C₈ = 89 congeners). There is a need for clear and unambiguous chemical shorthand to ensure accuracy and consistency in the future perfluorinated alkyl substance (PFA) literature, and to correct previous misconceptions that may have restricted research efforts into developing full-congener PFA analysis. If adopted by the research community, introduction of a numbering system at this relatively early stage of investigations into the congener-specific analysis, environmental behavior, and toxicology of PFAs would not require an arduous and difficult reassignment of historical structures and naming conventions presented in the prior art. Many PFA congeners are chiral, necessitating a consideration of their enantiospecific environmental behavior and toxicology.

Keywords:

• Perfluorinated alkyl substances
• congener-specific numbering system
• chiral compounds
• alkyl sulfonates and carboxylates
• telomer alcohols
• olefins
• acids

S. Rayne thanks the Natural Sciences and Engineering Research Council (NSERC) for financial support.

Notes

^a Note that the number of PFCA congeners is determined by applying the (n-1) rule, and the number of PFTAl/PFTOl/PFTAc congeners is determined by applying the (n-2) rule.